Planetary cooler for rotary tube furnace

ABSTRACT

A planetary cooler for a rotary tube furnace has a plurality of circumferentially spaced, individual holders extending radially of the furnace and in each of which is mounted a cooling tube. First abutment means is fixed on each of the holders and second abutment means is fixed on the adjacent holder in radially abutting, circumferentially slidable relation with the first abutment means.

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PLANETARY COOLER FOR ROTARY TUBE FURNACE FOREIGN PATENTS OR APPLICATIONS ,l49,29l 5/1963 Germany 432/106 [75] Inventors: Otto Heinemann, Ennigerloh;

Heinz-Herbert Schmits, Rheda; Hans Schulz, Rheinhausen, all of Primary Examiner-John J. Camby Germany Attorney, Agent, or Firm-Learman & McCulloch [73] Assignee: Polysius AG, Newbeckum, Germany Filed: Feb. 19, 1974 ABSTRACT [211 Appl. No.: 443,812

A planetary cooler for a rotary tube furnace has a plurality of circumferentially spaced, individual holders extending radiallyof the furnace and in each of which [30] Foreign Application Priority Data Feb. 28, I973 Germany..........r................. 2309883 is mounted a cooling tube. First abutment means is fixed on each of the holders and second abutment means is fixed on the adjacent holder in radially abutting, circumferentially slidable relation with the first abutment means.

686 030 1 N b0 78 N 0 3 $2 2mm m b 7" m mm UUC "He ms L cl C d Stud ll U.| .F 11]] 2 00 555 [ll References Cited UNITED STATES PATENTS 10 Claims, 2 Drawing Figures 3,502,139 3/1970 Andersen.............................. 432/80 PLANETARY COOLER FOR ROTARY TUBE FURNACE This invention relates to a rotary tube furnace and more particularly to a planetary cooler with a number of cooling tubes mounted on the periphery of a rotary tube furnace and which are affixed to the furnace casing by means of individual holders which permit thermal expansion of the cooling tubes and their holders in the peripheral direction.

It is known (from US. Pat. No. 3,503,139) to support the cooling tubes of a planetary cooler in an annular support plate affixed to the periphery of the rotary tube furnace which is provided with generally semicircular apertures to receive the cooling tubes. The cooling tubes are affixed in these apertures by clamp-like external fastening members. The main disadvantage of this arrangement is that the cooling tubes, which in operation undergo high thermal stresses, cannot expand freely, especially in the peripheral direction; the same applies to the webs of the one-piece support plate found between the apertures. If the cooling tubes are inserted in these apertures with no freedom to move, which must be the case for at least one point in the longitudinal direction of the tubes, considerable thermal stresses are inevitable in the cooling tubes, the annular support plate, and in the furnace casing.

In another known planetary cooler, the cooling tubes are affixed to stilt-like support members whose feet are pivotally connected to the rotary tube furnace casing (so that the cooling tubes can expand freely in the longitudinal direction), and whose outer ends are rigidly connected to the two cooling tubes located on different sides of the stilt-like support members. This arrangement also has the disadvantage that the cooling tubes are not free to expand in the peripheral direction to compensate for thermal stresses.

A further construction has been developed to overcome these faults and wherein the individual cooling tubes are affixed in separate holders whose inner ends are connected to the rotary tube furnace casing, and between which there is left free a gap in the peripheral direction to allow thermal expansion of the cooling tubes and of their holders in the peripheral direction. With this construction there arises, however, a further disadvantage. Because of the weight of the individual cooling tubes being applied eccentrically of the rotary tube furnace axis, very considerable tensile and pressure forces are produced at the feet of the cooling tube holders, i.e., in the area of the joint between these holders and the furnace casing and these forces apply heavy stresses to this joint and to the furnace casing.

The invention hereinafter disclosed is designed to avoid the aforementioned defects while providing a planetary cooler of the type initially described which is constructed in such manner that, while maintaining free expansion of the cooling tubes and of their holders in the peripheral direction, the stress on the joint between the cooling tube holders and the rotary tube furnace casing, and the stress on the rotary tube furnace casing itself are considerably reduced.

According to the invention this objective is achieved in that the holders for adjacent cooling tubes are radially abutted against each other. With abutment of this type, the tensile and pressure forces which, with the last described arrangement are transmitted to the casing of the rotary tube furnace, are compensated in the actual area of the adjacent holders so that the joint areas be tween the holders and the furnace casing, and the casing itself, are only subjected to appreciably smaller differential forces (transverse forces acting substantially radially).

The abutment in the radial direction of the holders for adjacent cooling tubes enables these holders and the tubes to expand thermally with freedom in the peripheral direction, with the gap between adjacent holders becoming correspondingly smaller. With regard to thermal expansion in the radial direction, the abutment provided in accordance with the invention is not harm ful, since the adjacent cooling tubes and their holders expand approximately equally in the radial direction.

One embodiment of the invention, which also exhibits further effective embodiments thereof, is shown in the drawings, wherein:

FIG. 1 is a partial section through two cooling tubes of a planetary cooler in accordance with the invention; and

FIG. 2 is a sectional detail taken on the line II-II of FIG. 1 and showing the abutment of adjacent holders.

On the periphery of a rotary tube furnace l are mounted a number of cooling tubes 2, 2' etc. In the following description it is assumed that the axis 3 of cooling tube 2 lies at the level of the axis (not shown) of the rotary tube furnace l.

The cooling tube 2, and the same applies for all the other cooling tubes which are arranged in planetary fashion on the periphery of the rotary tube furnace 1, is mounted in a holder consisting of an inner holder member 4 and an outer holder member 5. The inner holder member 4 is rigidly attached to the casing of rotary tube furnace l and forms a generally semi-circular aperture 4a wherein the cooling tube 2 rests. The outer holder member 5 also has a generally semi-circular aperture 5a embracing the cooling tube 2, and is connected on both sides to the inner holder member 4 by jointing elements 6, 7 (for instance threaded bolts) which are only schematically indicated.

Between the holders of adjacent cooling tubes 2, 2' there is left a free gap 8 which permits thermal expansion of the cooling tubes and their holders in the peripheral direction.

Thus far the planetary cooler in accordance with the invention coincides with a known construction described above. Without the abutment provided by the invention and described in detail below, appreciable tensile and pressure forces Z and D would occur in the area of the joint between the inner holder member 4 and the casing of rotary tube furnace, caused by the weight of the cooling tube 2 and its holder 4, 5 (represented by the force K acting through the axis 3). The said forces are indicated by K, Z and D for cooling tube 2'.

In order to reduce these forces which stress the construction in undesirable manner, in accordance with the invention an abutment is provided between the holders of adjacent cooling tubes. Each of these abutments has three support members 9, 10, 11, whereby the radially innermost support member 9 and the radially putermost support member 11 are connected to the holder for one cooling tube (e.g., 2), in the present case the inner holder member 4, while the central or intermediate support member 10 is connected to the inner holder for the adjacent cooling tube (e.g., 2'). As shown especially in FIG. 2, these support members 9, 10, 11 have between them wedges l2 15 whereby irregularities in assembly can be compensated, and reliable mutual abutment of the support members 9, 10, 11 in the radial direction is ensured.

As shown in FIG. 1, the thickness in the peripheral direction of the individual support members 9 11 and of the individual wedges 12 15 is less than the width of the gap 8. This dimensioning ensures that the holders for neighboring cooling tubes 2, 2' can expand peripherally in relation to each other even in the abutment area.

In the embodiment shown, the center support member 10 is beveled at an angle complementary to wedges 12 15, thus producing a very good surface joint.

On consideration of FIG. 1 it will be clear that the undesirable forces Z, D or Z, D are considerably reduced by the radial abutment, in accordance with the invention, of the holders for adjacent cooling tubes, since in the area of the abutment there is already considerable compensation of the tension and pressure forces which arise. Consequently, only considerably reduced differential forces act on the joint area between the holders and the furnace casing, and on the casing itself.

In the embodiment described the abutment is provided between the inner holder members 4 for adjacent cooling tubes 2, 2. It is obviously also possible within the scope of the invention to dispose the abutment between the outer holder members 5 for adjacent cooling tubes. It is, however, desirable to dispose the abutment as far as possible into the outer area of the opposite surfaces of adjacent holders, i.e., to a point as far outward as possible in the radial direction.

What is claimed is:

1. In a rotary tube furnace of the like having a number of spaced, planetary cooling tubes mounted on the furnace by means of spaced, individual tube holders permitting thermal expansion of the tubes and holders in the peripheral direction, the combination of abutments on the holders of adjacent tubes, said abutments being in abutting engagement in the radial direction, said abutments each comprising at least two support members on one holder and at least one support member on the adjacent holder, said one support member being interposed between said two support members.

2. The construction according to claimv 1 wherein said abutments are spaced radially from said furnace.

3. The construction according to claim 1 wherein the individual tube holders each comprise inner and outer members in clamping relation about the associate tube.

4. The construction according to claim 3 wherein said abutments are on the inner members of said tube holders.

5. The construction according to claim 4 wherein said abutments are adjacent the outer ends of said inner members.

6. The construction according to claim 1 wherein said abutments each comprise at least two support members on one holder and at least one support member on the adjacent holder, said one support member being interposed between said two support members.

7. The construction according to claim 1 wherein the dimension of each of said support members in the peripheral direction is less than the spacing between adjacent holders.

8. The construction according to claim 1 including wedge means interposed between and seating on said one support member and said two support members.

9. The construction according to claim 8 wherein at least one of said support members has a surface on which said wedge means seats and which is beveled to complement said wedge means.

10. A rotary furnace construction comprising a rotary tube, a plurality of cooling tubes encircling said rotary tube in planetary arrangement; and means mounting each of said cooling tubes on said rotary tube, said mounting means comprising an individual holder for each of said cooling tubes fixed to said rotary tube and having an aperture therein in which the associated cooling tube is accommodated, adjacent ones of said holders being spaced from each other by a gap to permit thermal expansion thereof peripherally of said rotary tube, and abutments on adjacent ones of said holders in abutting engagement radially of said rotary tube. a: 

1. In a rotary tube furnace of the like having a number of spaced, planetary cooling tubes mounted on the furnace by means of spaced, individual tube holders permitting thermal expansion of the tubes and holders in the peripheral direction, the combination of abutments on the holders of adjacent tubes, said abutments being in abutting engagement in the radial direction, said abutments each comprising at least two support members on one holder and at least one support member on the adjacent holder, said one support member being interposed between said two support members.
 2. The construction according to claim 1 wherein said abutments are spaced radially from said furnace.
 3. The construction according to claim 1 wherein the individual tube holders each comprise inner and outer members in clamping relation about the associate tube.
 4. The construction according to claim 3 wherein said abutments are on the inner members of said tube holders.
 5. The construction according to claim 4 wherein said abutments are adjacent the outer ends of said inner members.
 6. The construction according to claim 1 wherein said abutments each comprise at least two support members on one holder and at least one support member on the adjacent holder, said one support member being interposed between said two support members.
 7. The construction according to claim 1 wherein the dimension of each of said support members in the peripheral direction is less than the spacing between adjacent holders.
 8. The construction according to claim 1 including wedge means interposed between and seating on said one support member and said two support members.
 9. The construction according to claim 8 wherein at least one of said support members has a surface on which said wedge means seats and which is beveled to complement said wedge means.
 10. A rotary furnace construction comprising a rotary tube, a plurality of cooling tubes encircling said rotary tube in planetary arrangement; and means mounting each of said cooling tubes on said rotary tube, said mounting means comprising an individual holder for each of said cooling tubes fixed to said rotary tube and having an aperture therein in which the associated cooling tube is accommodated, adjacent ones of said holders being spaced from each other by a gap to permit thermal expansion thereof peripherally of said rotary tube, and abutments on adjacent ones of said holders in abutting engagement radially of said rotary tube. 